Updated: November 1, 2021 2:03:12 am
This October, Delhi’s air has been the cleanest for the month at least since 2018. The average air quality index for October this year is 173, while the figure for October 2020 was 265. The corresponding figure for 2019 was 233, while in 2018, October recorded an average AQI of 268.
Experts have attributed this to record rainfall seen this monsoon. The delayed withdrawal of the monsoon this year, along with the presence of a western disturbance, brought rainfall to Delhi this October.
Bulletins of the Central Pollution Control Board (CPCB) also indicate that Delhi recorded no ‘very poor’ or ‘severe’ AQI day in October this year. This is in contrast to nine ‘very poor’ air days in 2020, five such days in 2019, and nine such days in 2018. In 2019, October recorded two ‘severe’ AQI days, while one such day was registered in 2018.
Delhi recorded its first ‘good’ air day in October this year — on October 18 when the AQI stood at 46. From 2018 onwards at least, the month of October has never recorded a ‘good’ air day.
This year, October recorded three days of ‘satisfactory’ AQI, while no such days of satisfactory AQI were recorded in 2020 and 2018 in October.
Active fire events up in Punjab, Haryana
Active fire events in Punjab and Haryana appear to have picked up over the past few days, after having fallen around October 24 and 25, when parts of northwest India received rainfall under the influence of a western disturbance.
In contrast, the share of crop residue burning to PM 2.5 levels in Delhi has fallen recently, since wind direction has not been favourable for transport of pollutants, according to scientists associated with the System of Air Quality and Weather Forecasting And Research (SAFAR) forecasting system.
On October 29, the active fire count in Punjab was 1,353, going by the CPCB bulletin issued on October 30. This is the highest active fire count for a single day from at least October 16 onwards.
The active fire count in Punjab has been increasing from October 26 onwards. On October 25, 76 fire events were recorded, followed by 329 on October 26, and 279 on October 27. The figure jumped to 761 on October 28, and crossed 1,000 on October 29. The last time that active fire counts over a thousand were recorded was on October 22, when 1,111 fire events were reported.
The active fire count for Haryana was 161 on October 29, up from around 134 on October 28, and 93 on October 27.
Delhi’s air quality remained in the ‘poor’ category for the fifth consecutive day on Sunday, with an AQI of 289. The contribution of stubble burning to PM 2.5 levels in Delhi was 8% on Sunday, down from 12% on October 30, and around 20% on October 29.
Wind direction began shifting recently, explaining the low contribution of stubble burning to pollutants in Delhi. As per the Air Quality Early Warning System, wind direction is likely to be from the southeast direction of Delhi on November 1 and 2. Winds from northwest or west usually bring in pollutants from burning.
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